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NumberField.places() does not return homomorphisms to RIF/CIF #31604

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mathehertogh mannequin opened this issue Apr 3, 2021 · 1 comment
Open

NumberField.places() does not return homomorphisms to RIF/CIF #31604

mathehertogh mannequin opened this issue Apr 3, 2021 · 1 comment

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@mathehertogh
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mathehertogh mannequin commented Apr 3, 2021

For K a number field, K.places() returns homomorphisms into RealField(106) and ComplexField(53). For example:

sage: K.<a> = NumberField(x^3-2)
sage: K.places()
[Ring morphism:
   From: Number Field in a with defining polynomial x^3 - 2
   To:   Real Field with 106 bits of precision
   Defn: a |--> 1.259921049894873164767210607278,
 Ring morphism:
   From: Number Field in a with defining polynomial x^3 - 2
   To:   Complex Field with 53 bits of precision
   Defn: a |--> -0.629960524947437 + 1.09112363597172*I]

While the documentation reads:

   Return the collection of all infinite places of self.

   By default, this returns the set of real places as homomorphisms
   into RIF first, followed by a choice of one of each pair of complex
   conjugate homomorphisms into CIF.

   On the other hand, if prec is not None, we simply return places
   into RealField(prec) and ComplexField(prec) (or RDF, CDF if
   prec=53).

I checked the implementation and it would be a simple and quick fix to actually return morphisms into RIF/CIF. But I don't know if that is what is actually wanted?
Quite some code now uses this function the way it currently is.

Either the documentation should be updated, or the code should be adjusted. I am willing to do it, but don't know which of the two options.

Component: number fields

Issue created by migration from https://trac.sagemath.org/ticket/31604

@mathehertogh mathehertogh mannequin added this to the sage-9.3 milestone Apr 3, 2021
@mkoeppe
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mkoeppe commented May 10, 2021

comment:1

Moving to 9.4, as 9.3 has been released.

@mkoeppe mkoeppe modified the milestones: sage-9.3, sage-9.4 May 10, 2021
@mkoeppe mkoeppe modified the milestones: sage-9.4, sage-9.5 Aug 22, 2021
@mkoeppe mkoeppe modified the milestones: sage-9.5, sage-9.6 Dec 18, 2021
@mkoeppe mkoeppe modified the milestones: sage-9.6, sage-9.7 May 3, 2022
@mkoeppe mkoeppe modified the milestones: sage-9.7, sage-9.8 Sep 19, 2022
@mkoeppe mkoeppe removed this from the sage-9.8 milestone Jan 29, 2023
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